<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>

        .snow {
            width: 40px;
            height: auto;
            position: absolute;
            display: block;
            animation: slowDown 2s linear infinite, rotate 1s linear infinite;
        }

        .container {
            height: 300px;
            width: 300px;
            outline: 1px solid red;
            position: relative;
            line-height: 300px;
            text-align: center;
            font-size: 50px;
        }

        @keyframes rotate {
            0% {
                transform: rotate(0deg);
            }
            100% {
                transform: rotate(360deg);
            }
        }

        @keyframes slowDown {
            0% {
                top: -40px;
                left: 20px;
                width: 0px;
            }
            20% {
                left: 0px;
                width: 40px;
            }
            80% {
                left: 0px;
                width: 40px;
            }
            100% {
                top: 300px;
                left: 20px;
                width: 0px;
            }
        }

    </style>
</head>
<body>
    <div class="container">
        <img class="snow" src="https://img0.baidu.com/it/u=3044590634,2365549503&fm=253&fmt=auto&app=138&f=JPG?w=500&h=500" alt="">
        hello
    </div>
</body>
</html>